The present invention relates to a disconnection detecting device, a signal processing unit and a disconnection detection method.
Conventionally, there are notification systems that inform of emergency. In these notification systems, for example, a communication unit and a signal processing unit are connected via connection wires. Although a transmission line from the signal processing unit to the communication unit is normal, in a case where a reception line from the communication unit to the signal processing unit is abnormal, emergency information cannot be received normally by the signal processing unit, whereby signal processing cannot be executed in the signal processing unit at a later stage.
Incidentally, for example, Patent Literature 1 describes a detection method as a method for detecting abnormality in such a notification system. In a notification system for informing of emergency described in Patent Literature 1, a predetermined sound signal in an audible frequency band is emitted from a speaker as an activation message when the system is activated to inform a user of the activation of the system, and a loop-back signal that is a signal resulting from inputting the emitted predetermined sound signal through a microphone is detected and analyzed, to thereby diagnose the abnormality of the emergency notification system.
[Patent Literature 1] Japanese Patent Publication No. 3775233